Short-term intense exercise is a natural, quantifiable stimulus of the adrenal cortex and medulla as well as of the sympathetic nervous system. We would like to employ a standard cycle ergometer exercise protocol to study the adrenomedullary and systemic sympathetic function of patients with CAH. This protocol has been run by the Clinical Center Rehabilitation Medicine Department (RMD) for 10 years. No serious adverse effects have been observed or reported in adults and children with a healthy cardiovascular system.